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/* |
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* Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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|
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package java.util; |
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|
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import java.util.concurrent.atomic.AtomicLong; |
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import java.util.Spliterator; |
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import java.util.function.IntConsumer; |
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import java.util.function.LongConsumer; |
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import java.util.function.DoubleConsumer; |
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import java.util.stream.StreamSupport; |
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import java.util.stream.IntStream; |
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import java.util.stream.LongStream; |
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import java.util.stream.DoubleStream; |
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|
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/** |
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* A generator of uniform pseudorandom values applicable for use in |
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* (among other contexts) isolated parallel computations that may |
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* generate subtasks. Class SplittableRandom supports methods for |
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* producing pseudorandom numbers of type {@code int}, {@code long}, |
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* and {@code double} with similar usages as for class |
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* {@link java.util.Random} but differs in the following ways: |
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* |
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* <ul> |
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* |
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* <li>Series of generated values pass the DieHarder suite testing |
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* independence and uniformity properties of random number generators. |
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* (Most recently validated with <a |
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* href="http://www.phy.duke.edu/~rgb/General/dieharder.php"> version |
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* 3.31.1</a>.) These tests validate only the methods for certain |
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* types and ranges, but similar properties are expected to hold, at |
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* least approximately, for others as well. </li> |
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* |
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* <li> Method {@link #split} constructs and returns a new |
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* SplittableRandom instance that shares no mutable state with the |
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* current instance. However, with very high probability, the |
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* values collectively generated by the two objects have the same |
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* statistical properties as if the same quantity of values were |
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* generated by a single thread using a single {@code |
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* SplittableRandom} object. </li> |
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* |
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* <li>Instances of SplittableRandom are <em>not</em> thread-safe. |
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* They are designed to be split, not shared, across threads. For |
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* example, a {@link java.util.concurrent.ForkJoinTask |
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* fork/join-style} computation using random numbers might include a |
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* construction of the form {@code new |
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* Subtask(aSplittableRandom.split()).fork()}. |
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* |
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* <li>This class provides additional methods for generating random |
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* streams, that employ the above techniques when used in {@code |
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* stream.parallel()} mode.</li> |
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* |
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* </ul> |
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* |
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* @author Guy Steele |
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* @author Doug Lea |
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* @since 1.8 |
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*/ |
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public class SplittableRandom { |
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|
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/* |
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* File organization: First the non-public methods that constitute |
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* the main algorithm, then the main public methods, followed by |
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* some custom spliterator classes needed for stream methods. |
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* |
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* Credits: Primary algorithm and code by Guy Steele. Stream |
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* support methods by Doug Lea. Documentation jointly produced |
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* with additional help from Brian Goetz. |
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*/ |
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|
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/* |
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* Implementation Overview. |
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* |
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* This algorithm was inspired by the "DotMix" algorithm by |
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* Leiserson, Schardl, and Sukha "Deterministic Parallel |
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* Random-Number Generation for Dynamic-Multithreading Platforms", |
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* PPoPP 2012, but improves and extends it in several ways. |
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* |
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* The primary update step (see method nextSeed()) is simply to |
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* add a constant ("gamma") to the current seed, modulo a prime |
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* ("George"). However, the nextLong and nextInt methods do not |
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* return this value, but instead the results of bit-mixing |
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* transformations that produce more uniformly distributed |
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* sequences. |
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* |
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* "George" is the otherwise nameless (because it cannot be |
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* represented) prime number 2^64+13. Using a prime number larger |
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* than can fit in a long ensures that all possible long values |
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* can occur, plus 13 others that just get skipped over when they |
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* are encountered; see method addGammaModGeorge. For this to |
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* work, initial gamma values must be at least 13. |
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* |
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* The value of gamma differs for each instance across a series of |
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* splits, and is generated using a slightly stripped-down variant |
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* of the same algorithm, but operating across calls to split(), |
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* not calls to nextSeed(): Each instance carries the state of |
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* this generator as nextSplit, and uses mix64(nextSplit) as its |
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* own gamma value. Computations of gammas themselves use a fixed |
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* constant as the second argument to the addGammaModGeorge |
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* function, GAMMA_GAMMA, a "genuinely random" number from a |
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* radioactive decay reading (obtained from |
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* http://www.fourmilab.ch/hotbits/) meeting the above range |
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* constraint. Using a fixed constant maintains the invariant that |
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* the value of gamma is the same for every instance that is at |
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* the same split-distance from their common root. (Note: there is |
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* nothing especially magic about obtaining this constant from a |
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* "truly random" physical source rather than just choosing one |
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* arbitrarily; using "hotbits" was merely an aesthetically pleasing |
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* choice. In either case, good statistical behavior of the |
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* algorithm should be, and was, verified by using the DieHarder |
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* test suite.) |
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* |
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* The mix64 bit-mixing function called by nextLong and other |
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* methods computes the same value as the "64-bit finalizer" |
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* function in Austin Appleby's MurmurHash3 algorithm. See |
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* http://code.google.com/p/smhasher/wiki/MurmurHash3 , which |
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* comments: "The constants for the finalizers were generated by a |
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* simple simulated-annealing algorithm, and both avalanche all |
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* bits of 'h' to within 0.25% bias." It also appears to work to |
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* use instead any of the variants proposed by David Stafford at |
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* http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html |
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* but these variants have not yet been tested as thoroughly |
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* in the context of the implementation of SplittableRandom. |
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* |
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* The mix32 function used for nextInt just consists of two of the |
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* five lines of mix64; avalanche testing shows that the 64-bit result |
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* has its top 32 bits avalanched well, though not the bottom 32 bits. |
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* DieHarder tests show that it is adequate for generating one |
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* random int from the 64-bit result of nextSeed. |
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* |
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* Support for the default (no-argument) constructor relies on an |
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* AtomicLong (defaultSeedGenerator) to help perform the |
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* equivalent of a split of a statically constructed |
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* SplittableRandom. Unlike other cases, this split must be |
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* performed in a thread-safe manner. We use |
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* AtomicLong.compareAndSet as the (typically) most efficient |
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* mechanism. To bootstrap, we start off using System.nanotime(), |
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* and update using another "genuinely random" constant |
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* DEFAULT_SEED_GAMMA. The default constructor uses GAMMA_GAMMA, |
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* not 0, for its splitSeed argument (addGammaModGeorge(0, |
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* GAMMA_GAMMA) == GAMMA_GAMMA) to reflect that each is split from |
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* this root generator, even though the root is not explicitly |
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* represented as a SplittableRandom. |
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*/ |
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|
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/** |
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* The "genuinely random" value for producing new gamma values. |
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* The value is arbitrary, subject to the requirement that it be |
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* greater or equal to 13. |
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*/ |
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private static final long GAMMA_GAMMA = 0xF2281E2DBA6606F3L; |
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|
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/** |
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* The "genuinely random" seed update value for default constructors. |
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* The value is arbitrary, subject to the requirement that it be |
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* greater or equal to 13. |
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*/ |
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private static final long DEFAULT_SEED_GAMMA = 0xBD24B73A95FB84D9L; |
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|
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/** |
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* The least non-zero value returned by nextDouble(). This value |
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* is scaled by a random value of 53 bits to produce a result. |
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*/ |
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private static final double DOUBLE_UNIT = 1.0 / (1L << 53); |
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|
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/** |
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* The next seed for default constructors. |
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*/ |
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private static final AtomicLong defaultSeedGenerator = |
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new AtomicLong(System.nanoTime()); |
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|
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/** |
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* The seed, updated only via method nextSeed. |
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*/ |
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private long seed; |
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|
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/** |
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* The constant value added to seed (mod George) on each update. |
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*/ |
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private final long gamma; |
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|
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/** |
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* The next seed to use for splits. Propagated using |
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* addGammaModGeorge across instances. |
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*/ |
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private final long nextSplit; |
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|
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/** |
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* Adds the given gamma value, g, to the given seed value s, mod |
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* George (2^64+13). We regard s and g as unsigned values |
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* (ranging from 0 to 2^64-1). We add g to s either once or twice |
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* (mod George) as necessary to produce an (unsigned) result less |
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* than 2^64. We require that g must be at least 13. This |
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* guarantees that if (s+g) mod George >= 2^64 then (s+g+g) mod |
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* George < 2^64; thus we need only a conditional, not a loop, |
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* to be sure of getting a representable value. |
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* |
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* @param s a seed value |
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* @param g a gamma value, 13 <= g (as unsigned) |
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*/ |
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private static long addGammaModGeorge(long s, long g) { |
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long p = s + g; |
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if (Long.compareUnsigned(p, g) >= 0) |
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return p; |
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long q = p - 13L; |
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return (Long.compareUnsigned(p, 13L) >= 0) ? q : (q + g); |
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} |
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|
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/** |
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* Returns a bit-mixed transformation of its argument. |
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* See above for explanation. |
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*/ |
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private static long mix64(long z) { |
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z ^= (z >>> 33); |
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z *= 0xff51afd7ed558ccdL; |
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z ^= (z >>> 33); |
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z *= 0xc4ceb9fe1a85ec53L; |
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z ^= (z >>> 33); |
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return z; |
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} |
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|
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/** |
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* Returns a bit-mixed int transformation of its argument. |
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* See above for explanation. |
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*/ |
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private static int mix32(long z) { |
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z ^= (z >>> 33); |
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z *= 0xc4ceb9fe1a85ec53L; |
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return (int)(z >>> 32); |
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} |
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|
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/** |
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* Internal constructor used by all other constructors and by |
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* method split. Establishes the initial seed for this instance, |
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* and uses the given splitSeed to establish gamma, as well as the |
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* nextSplit to use by this instance. The loop to skip ineligible |
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* gammas very rarely iterates, and does so at most 13 times. |
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*/ |
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private SplittableRandom(long seed, long splitSeed) { |
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this.seed = seed; |
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long s = splitSeed, g; |
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do { // ensure gamma >= 13, considered as an unsigned integer |
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s = addGammaModGeorge(s, GAMMA_GAMMA); |
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g = mix64(s); |
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} while (Long.compareUnsigned(g, 13L) < 0); |
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this.gamma = g; |
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this.nextSplit = s; |
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} |
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|
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/** |
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* Updates in-place and returns seed. |
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* See above for explanation. |
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*/ |
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private long nextSeed() { |
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return seed = addGammaModGeorge(seed, gamma); |
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} |
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|
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/** |
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* Atomically updates and returns next seed for default constructor. |
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*/ |
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private static long nextDefaultSeed() { |
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long oldSeed, newSeed; |
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do { |
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oldSeed = defaultSeedGenerator.get(); |
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newSeed = addGammaModGeorge(oldSeed, DEFAULT_SEED_GAMMA); |
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} while (!defaultSeedGenerator.compareAndSet(oldSeed, newSeed)); |
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return mix64(newSeed); |
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} |
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|
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/* |
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* Internal versions of nextX methods used by streams, as well as |
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* the public nextX(origin, bound) methods. These exist mainly to |
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* avoid the need for multiple versions of stream spliterators |
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* across the different exported forms of streams. |
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*/ |
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|
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/** |
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* The form of nextLong used by LongStream Spliterators. If |
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* origin is greater than bound, acts as unbounded form of |
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* nextLong, else as bounded form. |
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* |
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* @param origin the least value, unless greater than bound |
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* @param bound the upper bound (exclusive), must not equal origin |
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* @return a pseudorandom value |
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*/ |
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final long internalNextLong(long origin, long bound) { |
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/* |
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* Four Cases: |
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* |
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* 1. If the arguments indicate unbounded form, act as |
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* nextLong(). |
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* |
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* 2. If the range is an exact power of two, apply the |
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* associated bit mask. |
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* |
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* 3. If the range is positive, loop to avoid potential bias |
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* when the implicit nextLong() bound (2<sup>64</sup>) is not |
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* evenly divisible by the range. The loop rejects candidates |
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* computed from otherwise over-represented values. The |
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* expected number of iterations under an ideal generator |
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* varies from 1 to 2, depending on the bound. The loop itself |
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* takes an unlovable form. Because the first candidate is |
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* already available, we need a break-in-the-middle |
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* construction, which is concisely but cryptically performed |
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* within the while-condition of a body-less for loop. |
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* |
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* 4. Otherwise, the range cannot be represented as a positive |
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* long. The loop repeatedly generates unbounded longs until |
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* obtaining a candidate meeting constraints (with an expected |
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* number of iterations of less than two). |
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*/ |
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|
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long r = mix64(nextSeed()); |
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if (origin < bound) { |
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long n = bound - origin, m = n - 1; |
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if ((n & m) == 0L) // power of two |
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r = (r & m) + origin; |
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else if (n > 0L) { // reject over-represented candidates |
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for (long u = r >>> 1; // ensure nonnegative |
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u + m - (r = u % n) < 0L; // rejection check |
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u = mix64(nextSeed()) >>> 1) // retry |
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; |
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r += origin; |
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} |
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else { // range not representable as long |
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while (r < origin || r >= bound) |
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r = mix64(nextSeed()); |
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} |
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} |
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return r; |
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} |
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|
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/** |
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* The form of nextInt used by IntStream Spliterators. |
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* Exactly the same as long version, except for types. |
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* |
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* @param origin the least value, unless greater than bound |
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* @param bound the upper bound (exclusive), must not equal origin |
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* @return a pseudorandom value |
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*/ |
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final int internalNextInt(int origin, int bound) { |
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int r = mix32(nextSeed()); |
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if (origin < bound) { |
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int n = bound - origin, m = n - 1; |
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if ((n & m) == 0L) |
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r = (r & m) + origin; |
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else if (n > 0) { |
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for (int u = r >>> 1; |
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u + m - (r = u % n) < 0; |
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u = mix32(nextSeed()) >>> 1) |
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; |
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r += origin; |
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} |
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else { |
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while (r < origin || r >= bound) |
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r = mix32(nextSeed()); |
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} |
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} |
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return r; |
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} |
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|
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/** |
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* The form of nextDouble used by DoubleStream Spliterators. |
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* |
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* @param origin the least value, unless greater than bound |
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* @param bound the upper bound (exclusive), must not equal origin |
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* @return a pseudorandom value |
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*/ |
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final double internalNextDouble(double origin, double bound) { |
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double r = (nextLong() >>> 11) * DOUBLE_UNIT; |
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if (origin < bound) { |
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r = r * (bound - origin) + origin; |
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if (r >= bound) // correct for rounding |
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r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
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} |
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return r; |
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} |
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|
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/* ---------------- public methods ---------------- */ |
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|
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/** |
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* Creates a new SplittableRandom instance using the specified |
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* initial seed. SplittableRandom instances created with the same |
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* seed generate identical sequences of values. |
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* |
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* @param seed the initial seed |
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*/ |
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public SplittableRandom(long seed) { |
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this(seed, 0); |
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} |
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|
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/** |
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* Creates a new SplittableRandom instance that is likely to |
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* generate sequences of values that are statistically independent |
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* of those of any other instances in the current program; and |
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* may, and typically does, vary across program invocations. |
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*/ |
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public SplittableRandom() { |
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this(nextDefaultSeed(), GAMMA_GAMMA); |
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} |
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|
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/** |
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* Constructs and returns a new SplittableRandom instance that |
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* shares no mutable state with this instance. However, with very |
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* high probability, the set of values collectively generated by |
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* the two objects has the same statistical properties as if the |
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* same quantity of values were generated by a single thread using |
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* a single SplittableRandom object. Either or both of the two |
431 |
* objects may be further split using the {@code split()} method, |
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* and the same expected statistical properties apply to the |
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* entire set of generators constructed by such recursive |
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* splitting. |
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* |
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* @return the new SplittableRandom instance |
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*/ |
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public SplittableRandom split() { |
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return new SplittableRandom(nextSeed(), nextSplit); |
440 |
} |
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|
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/** |
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* Returns a pseudorandom {@code int} value. |
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* |
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* @return a pseudorandom {@code int} value |
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*/ |
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public int nextInt() { |
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return mix32(nextSeed()); |
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} |
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|
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/** |
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* Returns a pseudorandom {@code int} value between zero (inclusive) |
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* and the specified bound (exclusive). |
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* |
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* @param bound the bound on the random number to be returned. Must be |
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* positive. |
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* @return a pseudorandom {@code int} value between zero |
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* (inclusive) and the bound (exclusive). |
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* @throws IllegalArgumentException if the bound is less than zero |
460 |
*/ |
461 |
public int nextInt(int bound) { |
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if (bound <= 0) |
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throw new IllegalArgumentException("bound must be positive"); |
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// Specialize internalNextInt for origin 0 |
465 |
int r = mix32(nextSeed()); |
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int m = bound - 1; |
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if ((bound & m) == 0L) // power of two |
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r &= m; |
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else { // reject over-represented candidates |
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for (int u = r >>> 1; |
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u + m - (r = u % bound) < 0; |
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u = mix32(nextSeed()) >>> 1) |
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; |
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} |
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return r; |
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} |
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|
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/** |
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* Returns a pseudorandom {@code int} value between the specified |
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* origin (inclusive) and the specified bound (exclusive). |
481 |
* |
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* @param origin the least value returned |
483 |
* @param bound the upper bound (exclusive) |
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* @return a pseudorandom {@code int} value between the origin |
485 |
* (inclusive) and the bound (exclusive). |
486 |
* @throws IllegalArgumentException if {@code origin} is greater than |
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* or equal to {@code bound} |
488 |
*/ |
489 |
public int nextInt(int origin, int bound) { |
490 |
if (origin >= bound) |
491 |
throw new IllegalArgumentException("bound must be greater than origin"); |
492 |
return internalNextInt(origin, bound); |
493 |
} |
494 |
|
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/** |
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* Returns a pseudorandom {@code long} value. |
497 |
* |
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* @return a pseudorandom {@code long} value |
499 |
*/ |
500 |
public long nextLong() { |
501 |
return mix64(nextSeed()); |
502 |
} |
503 |
|
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/** |
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* Returns a pseudorandom {@code long} value between zero (inclusive) |
506 |
* and the specified bound (exclusive). |
507 |
* |
508 |
* @param bound the bound on the random number to be returned. Must be |
509 |
* positive. |
510 |
* @return a pseudorandom {@code long} value between zero |
511 |
* (inclusive) and the bound (exclusive). |
512 |
* @throws IllegalArgumentException if {@code bound} is less than zero |
513 |
*/ |
514 |
public long nextLong(long bound) { |
515 |
if (bound <= 0) |
516 |
throw new IllegalArgumentException("bound must be positive"); |
517 |
// Specialize internalNextLong for origin 0 |
518 |
long r = mix64(nextSeed()); |
519 |
long m = bound - 1; |
520 |
if ((bound & m) == 0L) // power of two |
521 |
r &= m; |
522 |
else { // reject over-represented candidates |
523 |
for (long u = r >>> 1; |
524 |
u + m - (r = u % bound) < 0L; |
525 |
u = mix64(nextSeed()) >>> 1) |
526 |
; |
527 |
} |
528 |
return r; |
529 |
} |
530 |
|
531 |
/** |
532 |
* Returns a pseudorandom {@code long} value between the specified |
533 |
* origin (inclusive) and the specified bound (exclusive). |
534 |
* |
535 |
* @param origin the least value returned |
536 |
* @param bound the upper bound (exclusive) |
537 |
* @return a pseudorandom {@code long} value between the origin |
538 |
* (inclusive) and the bound (exclusive). |
539 |
* @throws IllegalArgumentException if {@code origin} is greater than |
540 |
* or equal to {@code bound} |
541 |
*/ |
542 |
public long nextLong(long origin, long bound) { |
543 |
if (origin >= bound) |
544 |
throw new IllegalArgumentException("bound must be greater than origin"); |
545 |
return internalNextLong(origin, bound); |
546 |
} |
547 |
|
548 |
/** |
549 |
* Returns a pseudorandom {@code double} value between zero |
550 |
* (inclusive) and one (exclusive). |
551 |
* |
552 |
* @return a pseudorandom {@code double} value between zero |
553 |
* (inclusive) and one (exclusive) |
554 |
*/ |
555 |
public double nextDouble() { |
556 |
return (nextLong() >>> 11) * DOUBLE_UNIT; |
557 |
} |
558 |
|
559 |
/** |
560 |
* Returns a pseudorandom {@code double} value between 0.0 |
561 |
* (inclusive) and the specified bound (exclusive). |
562 |
* |
563 |
* @param bound the bound on the random number to be returned. Must be |
564 |
* positive. |
565 |
* @return a pseudorandom {@code double} value between zero |
566 |
* (inclusive) and the bound (exclusive). |
567 |
* @throws IllegalArgumentException if {@code bound} is less than zero |
568 |
*/ |
569 |
public double nextDouble(double bound) { |
570 |
if (!(bound > 0.0)) |
571 |
throw new IllegalArgumentException("bound must be positive"); |
572 |
double result = nextDouble() * bound; |
573 |
return (result < bound) ? result : // correct for rounding |
574 |
Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
575 |
} |
576 |
|
577 |
/** |
578 |
* Returns a pseudorandom {@code double} value between the specified |
579 |
* origin (inclusive) and bound (exclusive). |
580 |
* |
581 |
* @param origin the least value returned |
582 |
* @param bound the upper bound |
583 |
* @return a pseudorandom {@code double} value between the origin |
584 |
* (inclusive) and the bound (exclusive). |
585 |
* @throws IllegalArgumentException if {@code origin} is greater than |
586 |
* or equal to {@code bound} |
587 |
*/ |
588 |
public double nextDouble(double origin, double bound) { |
589 |
if (!(origin < bound)) |
590 |
throw new IllegalArgumentException("bound must be greater than origin"); |
591 |
return internalNextDouble(origin, bound); |
592 |
} |
593 |
|
594 |
// stream methods, coded in a way intended to better isolate for |
595 |
// maintenance purposes the small differences across forms. |
596 |
|
597 |
/** |
598 |
* Returns a stream producing the given {@code streamSize} number of |
599 |
* pseudorandom {@code int} values. |
600 |
* |
601 |
* @param streamSize the number of values to generate |
602 |
* @return a stream of pseudorandom {@code int} values |
603 |
* @throws IllegalArgumentException if {@code streamSize} is |
604 |
* less than zero |
605 |
*/ |
606 |
public IntStream ints(long streamSize) { |
607 |
if (streamSize < 0L) |
608 |
throw new IllegalArgumentException("negative Stream size"); |
609 |
return StreamSupport.intStream |
610 |
(new RandomIntsSpliterator |
611 |
(this, 0L, streamSize, Integer.MAX_VALUE, 0), |
612 |
false); |
613 |
} |
614 |
|
615 |
/** |
616 |
* Returns an effectively unlimited stream of pseudorandom {@code int} |
617 |
* values |
618 |
* |
619 |
* @implNote This method is implemented to be equivalent to {@code |
620 |
* ints(Long.MAX_VALUE)}. |
621 |
* |
622 |
* @return a stream of pseudorandom {@code int} values |
623 |
*/ |
624 |
public IntStream ints() { |
625 |
return StreamSupport.intStream |
626 |
(new RandomIntsSpliterator |
627 |
(this, 0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0), |
628 |
false); |
629 |
} |
630 |
|
631 |
/** |
632 |
* Returns a stream producing the given {@code streamSize} number of |
633 |
* pseudorandom {@code int} values, each conforming to the given |
634 |
* origin and bound. |
635 |
* |
636 |
* @param streamSize the number of values to generate |
637 |
* @param randomNumberOrigin the origin of each random value |
638 |
* @param randomNumberBound the bound of each random value |
639 |
* @return a stream of pseudorandom {@code int} values, |
640 |
* each with the given origin and bound. |
641 |
* @throws IllegalArgumentException if {@code streamSize} is |
642 |
* less than zero, or {@code randomNumberOrigin} |
643 |
* is greater than or equal to {@code randomNumberBound} |
644 |
*/ |
645 |
public IntStream ints(long streamSize, int randomNumberOrigin, |
646 |
int randomNumberBound) { |
647 |
if (streamSize < 0L) |
648 |
throw new IllegalArgumentException("negative Stream size"); |
649 |
if (randomNumberOrigin >= randomNumberBound) |
650 |
throw new IllegalArgumentException("bound must be greater than origin"); |
651 |
return StreamSupport.intStream |
652 |
(new RandomIntsSpliterator |
653 |
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
654 |
false); |
655 |
} |
656 |
|
657 |
/** |
658 |
* Returns an effectively unlimited stream of pseudorandom {@code |
659 |
* int} values, each conforming to the given origin and bound. |
660 |
* |
661 |
* @implNote This method is implemented to be equivalent to {@code |
662 |
* ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
663 |
* |
664 |
* @param randomNumberOrigin the origin of each random value |
665 |
* @param randomNumberBound the bound of each random value |
666 |
* @return a stream of pseudorandom {@code int} values, |
667 |
* each with the given origin and bound. |
668 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
669 |
* is greater than or equal to {@code randomNumberBound} |
670 |
*/ |
671 |
public IntStream ints(int randomNumberOrigin, int randomNumberBound) { |
672 |
if (randomNumberOrigin >= randomNumberBound) |
673 |
throw new IllegalArgumentException("bound must be greater than origin"); |
674 |
return StreamSupport.intStream |
675 |
(new RandomIntsSpliterator |
676 |
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
677 |
false); |
678 |
} |
679 |
|
680 |
/** |
681 |
* Returns a stream producing the given {@code streamSize} number of |
682 |
* pseudorandom {@code long} values. |
683 |
* |
684 |
* @param streamSize the number of values to generate |
685 |
* @return a stream of pseudorandom {@code long} values |
686 |
* @throws IllegalArgumentException if {@code streamSize} is |
687 |
* less than zero |
688 |
*/ |
689 |
public LongStream longs(long streamSize) { |
690 |
if (streamSize < 0L) |
691 |
throw new IllegalArgumentException("negative Stream size"); |
692 |
return StreamSupport.longStream |
693 |
(new RandomLongsSpliterator |
694 |
(this, 0L, streamSize, Long.MAX_VALUE, 0L), |
695 |
false); |
696 |
} |
697 |
|
698 |
/** |
699 |
* Returns an effectively unlimited stream of pseudorandom {@code long} |
700 |
* values. |
701 |
* |
702 |
* @implNote This method is implemented to be equivalent to {@code |
703 |
* longs(Long.MAX_VALUE)}. |
704 |
* |
705 |
* @return a stream of pseudorandom {@code long} values |
706 |
*/ |
707 |
public LongStream longs() { |
708 |
return StreamSupport.longStream |
709 |
(new RandomLongsSpliterator |
710 |
(this, 0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L), |
711 |
false); |
712 |
} |
713 |
|
714 |
/** |
715 |
* Returns a stream producing the given {@code streamSize} number of |
716 |
* pseudorandom {@code long} values, each conforming to the |
717 |
* given origin and bound. |
718 |
* |
719 |
* @param streamSize the number of values to generate |
720 |
* @param randomNumberOrigin the origin of each random value |
721 |
* @param randomNumberBound the bound of each random value |
722 |
* @return a stream of pseudorandom {@code long} values, |
723 |
* each with the given origin and bound. |
724 |
* @throws IllegalArgumentException if {@code streamSize} is |
725 |
* less than zero, or {@code randomNumberOrigin} |
726 |
* is greater than or equal to {@code randomNumberBound} |
727 |
*/ |
728 |
public LongStream longs(long streamSize, long randomNumberOrigin, |
729 |
long randomNumberBound) { |
730 |
if (streamSize < 0L) |
731 |
throw new IllegalArgumentException("negative Stream size"); |
732 |
if (randomNumberOrigin >= randomNumberBound) |
733 |
throw new IllegalArgumentException("bound must be greater than origin"); |
734 |
return StreamSupport.longStream |
735 |
(new RandomLongsSpliterator |
736 |
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
737 |
false); |
738 |
} |
739 |
|
740 |
/** |
741 |
* Returns an effectively unlimited stream of pseudorandom {@code |
742 |
* long} values, each conforming to the given origin and bound. |
743 |
* |
744 |
* @implNote This method is implemented to be equivalent to {@code |
745 |
* longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
746 |
* |
747 |
* @param randomNumberOrigin the origin of each random value |
748 |
* @param randomNumberBound the bound of each random value |
749 |
* @return a stream of pseudorandom {@code long} values, |
750 |
* each with the given origin and bound. |
751 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
752 |
* is greater than or equal to {@code randomNumberBound} |
753 |
*/ |
754 |
public LongStream longs(long randomNumberOrigin, long randomNumberBound) { |
755 |
if (randomNumberOrigin >= randomNumberBound) |
756 |
throw new IllegalArgumentException("bound must be greater than origin"); |
757 |
return StreamSupport.longStream |
758 |
(new RandomLongsSpliterator |
759 |
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
760 |
false); |
761 |
} |
762 |
|
763 |
/** |
764 |
* Returns a stream producing the given {@code streamSize} number of |
765 |
* pseudorandom {@code double} values, each between zero |
766 |
* (inclusive) and one (exclusive). |
767 |
* |
768 |
* @param streamSize the number of values to generate |
769 |
* @return a stream of {@code double} values |
770 |
* @throws IllegalArgumentException if {@code streamSize} is |
771 |
* less than zero |
772 |
*/ |
773 |
public DoubleStream doubles(long streamSize) { |
774 |
if (streamSize < 0L) |
775 |
throw new IllegalArgumentException("negative Stream size"); |
776 |
return StreamSupport.doubleStream |
777 |
(new RandomDoublesSpliterator |
778 |
(this, 0L, streamSize, Double.MAX_VALUE, 0.0), |
779 |
false); |
780 |
} |
781 |
|
782 |
/** |
783 |
* Returns an effectively unlimited stream of pseudorandom {@code |
784 |
* double} values, each between zero (inclusive) and one |
785 |
* (exclusive). |
786 |
* |
787 |
* @implNote This method is implemented to be equivalent to {@code |
788 |
* doubles(Long.MAX_VALUE)}. |
789 |
* |
790 |
* @return a stream of pseudorandom {@code double} values |
791 |
*/ |
792 |
public DoubleStream doubles() { |
793 |
return StreamSupport.doubleStream |
794 |
(new RandomDoublesSpliterator |
795 |
(this, 0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0), |
796 |
false); |
797 |
} |
798 |
|
799 |
/** |
800 |
* Returns a stream producing the given {@code streamSize} number of |
801 |
* pseudorandom {@code double} values, each conforming to the |
802 |
* given origin and bound. |
803 |
* |
804 |
* @param streamSize the number of values to generate |
805 |
* @param randomNumberOrigin the origin of each random value |
806 |
* @param randomNumberBound the bound of each random value |
807 |
* @return a stream of pseudorandom {@code double} values, |
808 |
* each with the given origin and bound. |
809 |
* @throws IllegalArgumentException if {@code streamSize} is |
810 |
* less than zero. |
811 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
812 |
* is greater than or equal to {@code randomNumberBound} |
813 |
*/ |
814 |
public DoubleStream doubles(long streamSize, double randomNumberOrigin, |
815 |
double randomNumberBound) { |
816 |
if (streamSize < 0L) |
817 |
throw new IllegalArgumentException("negative Stream size"); |
818 |
if (!(randomNumberOrigin < randomNumberBound)) |
819 |
throw new IllegalArgumentException("bound must be greater than origin"); |
820 |
return StreamSupport.doubleStream |
821 |
(new RandomDoublesSpliterator |
822 |
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
823 |
false); |
824 |
} |
825 |
|
826 |
/** |
827 |
* Returns an effectively unlimited stream of pseudorandom {@code |
828 |
* double} values, each conforming to the given origin and bound. |
829 |
* |
830 |
* @implNote This method is implemented to be equivalent to {@code |
831 |
* doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
832 |
* |
833 |
* @param randomNumberOrigin the origin of each random value |
834 |
* @param randomNumberBound the bound of each random value |
835 |
* @return a stream of pseudorandom {@code double} values, |
836 |
* each with the given origin and bound. |
837 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
838 |
* is greater than or equal to {@code randomNumberBound} |
839 |
*/ |
840 |
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) { |
841 |
if (!(randomNumberOrigin < randomNumberBound)) |
842 |
throw new IllegalArgumentException("bound must be greater than origin"); |
843 |
return StreamSupport.doubleStream |
844 |
(new RandomDoublesSpliterator |
845 |
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
846 |
false); |
847 |
} |
848 |
|
849 |
/** |
850 |
* Spliterator for int streams. We multiplex the four int |
851 |
* versions into one class by treating a bound less than origin as |
852 |
* unbounded, and also by treating "infinite" as equivalent to |
853 |
* Long.MAX_VALUE. For splits, it uses the standard divide-by-two |
854 |
* approach. The long and double versions of this class are |
855 |
* identical except for types. |
856 |
*/ |
857 |
static class RandomIntsSpliterator implements Spliterator.OfInt { |
858 |
final SplittableRandom rng; |
859 |
long index; |
860 |
final long fence; |
861 |
final int origin; |
862 |
final int bound; |
863 |
RandomIntsSpliterator(SplittableRandom rng, long index, long fence, |
864 |
int origin, int bound) { |
865 |
this.rng = rng; this.index = index; this.fence = fence; |
866 |
this.origin = origin; this.bound = bound; |
867 |
} |
868 |
|
869 |
public RandomIntsSpliterator trySplit() { |
870 |
long i = index, m = (i + fence) >>> 1; |
871 |
return (m <= i) ? null : |
872 |
new RandomIntsSpliterator(rng.split(), i, index = m, origin, bound); |
873 |
} |
874 |
|
875 |
public long estimateSize() { |
876 |
return fence - index; |
877 |
} |
878 |
|
879 |
public int characteristics() { |
880 |
return (Spliterator.SIZED | Spliterator.SUBSIZED | |
881 |
Spliterator.NONNULL | Spliterator.IMMUTABLE); |
882 |
} |
883 |
|
884 |
public boolean tryAdvance(IntConsumer consumer) { |
885 |
if (consumer == null) throw new NullPointerException(); |
886 |
long i = index, f = fence; |
887 |
if (i < f) { |
888 |
consumer.accept(rng.internalNextInt(origin, bound)); |
889 |
index = i + 1; |
890 |
return true; |
891 |
} |
892 |
return false; |
893 |
} |
894 |
|
895 |
public void forEachRemaining(IntConsumer consumer) { |
896 |
if (consumer == null) throw new NullPointerException(); |
897 |
long i = index, f = fence; |
898 |
if (i < f) { |
899 |
index = f; |
900 |
int o = origin, b = bound; |
901 |
do { |
902 |
consumer.accept(rng.internalNextInt(o, b)); |
903 |
} while (++i < f); |
904 |
} |
905 |
} |
906 |
} |
907 |
|
908 |
/** |
909 |
* Spliterator for long streams. |
910 |
*/ |
911 |
static class RandomLongsSpliterator implements Spliterator.OfLong { |
912 |
final SplittableRandom rng; |
913 |
long index; |
914 |
final long fence; |
915 |
final long origin; |
916 |
final long bound; |
917 |
RandomLongsSpliterator(SplittableRandom rng, long index, long fence, |
918 |
long origin, long bound) { |
919 |
this.rng = rng; this.index = index; this.fence = fence; |
920 |
this.origin = origin; this.bound = bound; |
921 |
} |
922 |
|
923 |
public RandomLongsSpliterator trySplit() { |
924 |
long i = index, m = (i + fence) >>> 1; |
925 |
return (m <= i) ? null : |
926 |
new RandomLongsSpliterator(rng.split(), i, index = m, origin, bound); |
927 |
} |
928 |
|
929 |
public long estimateSize() { |
930 |
return fence - index; |
931 |
} |
932 |
|
933 |
public int characteristics() { |
934 |
return (Spliterator.SIZED | Spliterator.SUBSIZED | |
935 |
Spliterator.NONNULL | Spliterator.IMMUTABLE); |
936 |
} |
937 |
|
938 |
public boolean tryAdvance(LongConsumer consumer) { |
939 |
if (consumer == null) throw new NullPointerException(); |
940 |
long i = index, f = fence; |
941 |
if (i < f) { |
942 |
consumer.accept(rng.internalNextLong(origin, bound)); |
943 |
index = i + 1; |
944 |
return true; |
945 |
} |
946 |
return false; |
947 |
} |
948 |
|
949 |
public void forEachRemaining(LongConsumer consumer) { |
950 |
if (consumer == null) throw new NullPointerException(); |
951 |
long i = index, f = fence; |
952 |
if (i < f) { |
953 |
index = f; |
954 |
long o = origin, b = bound; |
955 |
do { |
956 |
consumer.accept(rng.internalNextLong(o, b)); |
957 |
} while (++i < f); |
958 |
} |
959 |
} |
960 |
|
961 |
} |
962 |
|
963 |
/** |
964 |
* Spliterator for double streams. |
965 |
*/ |
966 |
static class RandomDoublesSpliterator implements Spliterator.OfDouble { |
967 |
final SplittableRandom rng; |
968 |
long index; |
969 |
final long fence; |
970 |
final double origin; |
971 |
final double bound; |
972 |
RandomDoublesSpliterator(SplittableRandom rng, long index, long fence, |
973 |
double origin, double bound) { |
974 |
this.rng = rng; this.index = index; this.fence = fence; |
975 |
this.origin = origin; this.bound = bound; |
976 |
} |
977 |
|
978 |
public RandomDoublesSpliterator trySplit() { |
979 |
long i = index, m = (i + fence) >>> 1; |
980 |
return (m <= i) ? null : |
981 |
new RandomDoublesSpliterator(rng.split(), i, index = m, origin, bound); |
982 |
} |
983 |
|
984 |
public long estimateSize() { |
985 |
return fence - index; |
986 |
} |
987 |
|
988 |
public int characteristics() { |
989 |
return (Spliterator.SIZED | Spliterator.SUBSIZED | |
990 |
Spliterator.NONNULL | Spliterator.IMMUTABLE); |
991 |
} |
992 |
|
993 |
public boolean tryAdvance(DoubleConsumer consumer) { |
994 |
if (consumer == null) throw new NullPointerException(); |
995 |
long i = index, f = fence; |
996 |
if (i < f) { |
997 |
consumer.accept(rng.internalNextDouble(origin, bound)); |
998 |
index = i + 1; |
999 |
return true; |
1000 |
} |
1001 |
return false; |
1002 |
} |
1003 |
|
1004 |
public void forEachRemaining(DoubleConsumer consumer) { |
1005 |
if (consumer == null) throw new NullPointerException(); |
1006 |
long i = index, f = fence; |
1007 |
if (i < f) { |
1008 |
index = f; |
1009 |
double o = origin, b = bound; |
1010 |
do { |
1011 |
consumer.accept(rng.internalNextDouble(o, b)); |
1012 |
} while (++i < f); |
1013 |
} |
1014 |
} |
1015 |
} |
1016 |
|
1017 |
} |